000 WTNT44 KNHC 271447 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 60 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 1100 AM AST THU SEP 27 2012 SATELLITE IMAGERY SHOWS THAT THE CONVECTION ASSOCIATED WITH NADINE HAS MOVED CLOSER TO THE CIRCULATION CENTER. HOWEVER...THE OVERALL CONVECTIVE PATTERN IS A LITTLE RAGGED AT THIS TIME. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE UNCHANGED SINCE 6 HR AGO...SO THE INITIAL INTENSITY REMAINS 50 KT. THE CIRRUS OUTFLOW IS FAIR IN THE NORTHERN SEMICIRCLE AND POOR ELSEWHERE. NADINE HAS TURNED WEST-SOUTHWESTWARD DURING THE PAST SEVERAL HOURS WITH THE INITIAL MOTION NOW 240/6. THE STORM IS ON THE SOUTH SIDE OF A DEEP-LAYER RIDGE...WHICH IS FORECAST TO MOVE EASTWARD DURING THE NEXT 48-72 HR. THIS WILL ALLOW NADINE TO TURN NORTHWESTWARD AND NORTHWARD AS IT MOVES BETWEEN THE RIDGE AND A MID/UPPER-LEVEL LOW CURRENTLY SEEN IN WATER VAPOR IMAGERY NEAR 29N48W. THE TRACK GUIDANCE IS IN GOOD AGREEMENT DURING THIS PART OF THE FORECAST PERIOD. AFTER THAT...THE GUIDANCE BECOMES VERY DIVERGENT. THE GFS...GFS ENSEMBLE MEAN...GFDL...AND HWRF FORECAST NADINE TO MOVE SLOWLY EASTWARD TO NORTHEASTWARD ALONG THE SOUTHERN EDGE OF THE WESTERLIES AS A TROUGH PASSES NORTH OF THE STORM. THE UKMET... ECMWF...CANADIAN...AND NOGAPS FORECAST A RIDGE TO BUILD NORTH AND NORTHWEST OF NADINE IN THE WAKE OF THE WESTERLY TROUGH...WHICH WOULD STEER THE STORM BACK TOWARD THE SOUTH OR SOUTHWEST. THE TRACK FORECAST CONTINUES TO SPLIT THE DIFFERENCE BETWEEN THESE EXTREMES AND SHOWS A SLOW MOTION AT 96-120 HR. THE NEW FORECAST TRACK LIES NEAR THE VARIOUS CONSENSUS MODELS THROUGH 72 HR...AFTER WHICH IT LIES WEST OF THE CONSENSUS MODELS. THE GLOBAL MODELS FORECAST NADINE TO INTERACT WITH THE MID/UPPER-LEVEL LOW NEAR 29N48W DURING THE FORECAST PERIOD...WITH THE TWO SYSTEMS POSSIBLY MERGING BY 96-120 HR. IN ADDITION...SMALL SHORTWAVE TROUGHS ROTATING AROUND THE LOW COULD ALSO INTERACT WITH THE STORM. WHILE THE GLOBAL MODELS FORECAST INCREASING UPPER-LEVEL WINDS NEAR NADINE...IT IS POSSIBLE THAT THE SHORTWAVE TROUGHS COULD PARTLY SHIELD NADINE FROM THE RESULTING SHEAR. THE STATISTICAL INTENSITY GUIDANCE IS FORECASTING A STRONGER STORM THAN IT DID DURING THE LAST ADVISORY CYCLE...WITH THE SHIPS AND LGEM MODELS NOW 5-10 KT HIGHER THAN THEY WERE 6 HR AGO. DUE TO THE UNCERTAINTY IN THE AMOUNT OF SHEAR...AND THE LIKELIHOOD THAT NADINE WILL MOVE OVER COOLER SEA SURFACE TEMPERATURES AFTER 36 HR...THE NEW INTENSITY FORECAST CONSERVATIVELY STAYS CLOSE TO THE PREVIOUS FORECAST. THE NEW FORECAST IS STRONGER THAN THE FLORIDA STATE SUPERENSEMBLE...BUT IS WEAKER THAN SHIPS...LGEM...AND THE INTENSITY CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 27/1500Z 28.7N 32.4W 50 KT 60 MPH 12H 28/0000Z 28.6N 33.4W 55 KT 65 MPH 24H 28/1200Z 29.0N 34.5W 55 KT 65 MPH 36H 29/0000Z 30.1N 35.3W 55 KT 65 MPH 48H 29/1200Z 31.5N 35.9W 55 KT 65 MPH 72H 30/1200Z 34.5N 36.5W 50 KT 60 MPH 96H 01/1200Z 35.5N 37.0W 50 KT 60 MPH 120H 02/1200Z 36.0N 37.0W 45 KT 50 MPH $$ FORECASTER BEVEN